Faraday made his first discovery of electromagnetism in As he explained years later, the wire was surrounded by an infinite series of circular concentric lines of force , which he termed the magnetic field of the current.
He found that when an electrical current was passed through a coil, another very short current was generated in a nearby coil. This discovery marked a decisive milestone in the progress not only of science but also of society , and is used today to generate electricity on a large scale in power stations. This phenomenon reveals something new about electric and magnetic fields.
Unlike electrostatic fields generated by electric charges at rest whose circulation along a closed path is zero a conservative field , the circulation of electric fields created by magnetic fields is along a closed path other than zero. Faraday invented the first electric motor, the first electrical transformer, the first electric generator and the first dynamo, so Faraday can be called, without any doubt, the father of electrical engineering.
As noted at the beginning of this article, another and perhaps less known effect discovered by Faraday was the influence of a magnetic field on polarized light, a phenomenon known as the Faraday effect or magneto-optical effect. He also wanted to determine whether magnetic fields had an effect on optical phenomena.
He believed in the unity of all the forces of nature, and in particular of light, electricity and magnetism. On September 13, he found that the plane of polarization of linearly polarized light is rotated when this light travels through a material to which a strong magnetic field is applied in the direction of propagation of the light.
Faraday wrote in paragraph of his Dairy :. This was certainly the first clear indication that magnetic force and light were related to each other and it also showed that light is related to electricity and magnetism. In relation to this phenomenon Faraday also wrote in the same paragraph:. The truth is that on this particular Friday it was Charles Wheatstone who was scheduled to give a talk on his chronoscope. Since he finished ahead of time, he filled in the remaining minutes by revealing his thoughts on the nature of light.
Faraday even dared to question the existence of the luminiferous aether —a scientific heresy at that time—, which was supposed to be the medium for light propagation as so elegantly Fresnel had described in his wave theory of light. He proposed that the light could be not the result of aether vibrations, but vibrations of the physical lines of force. Faraday tried to leave out the aether, but he kept the vibrations. In an almost apologetic tone, Faraday finishes his paper stating:.
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The electromagnetic waves about whose existence Faraday speculated in with his thoughts on ray vibrations , and which were mathematically predicted by Maxwell in , were finally produced in a laboratory by Hertz in The rest is history. It is clear that Maxwell opened the door to twentieth century physics, but it is no less clear that Faraday gave Maxwell some of the keys he used.
NPTEL :: Physics - Electromagnetic Theory
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Faraday and the Electromagnetic Theory of Light
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He is a theoretical physicist , whose chief interest lies in Electronic Structure of Atoms, Molecules and Solids using Density Functional. But if you want a certificate, you have to register and write the proctored exam conducted by us in person at any of the designated exam centres. Registration url: Announcements will be made when the registration form is open for registrations. The online registration form has to be filled and the certification exam fee needs to be paid. More details will be made available when the exam registration form is published.
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